Polyester resins, especially polyethylene terephthalate (PET) and its copolyesters, are widely used to produce rigid packaging, such as two-liter soft drink containers. Polyester packages produced by stretch-blow molding possess high strength and shatter resistance, and have excellent gas barrier and organoleptic properties as well. Consequently, such plastics have virtually replaced glass in packaging numerous consumer products (e.g. carbonated soft drinks, fruit juices, and peanut butter).
Polyethylene terephthalate bottles, such as straight-walled two-liter carbonated soft drink bottles, often possess high coefficients of friction (COF). In the bottling industry, this “sticky-bottle” problem is significant. Excessive friction between adjacent bottles prevents such bottles from easily and efficiently sliding past one another as they are depalletized. To improve depalletizing, bottlers conventionally resort to water misting and line lubrication on a filling line.
The aforementioned commonly assigned U.S. Pat. Nos. 6,500,890 and 6,710,158 disclose enhancing polyester resins with small amounts of inert particulates, namely talc and calcium carbonate. The resulting polyester resins are capable of yielding high-clarity preforms and bottles that possess reduced coefficients of friction, thereby addressing aspects of the “sticky-bottle” problem. Indeed, bottles formed from such resins reduce the need for external lubricants during depalletizing operations.
Nevertheless, there is a desire to provide alternative polymer resins that are capable of forming articles possessing increased clarity, reduced frictional characteristics, or both.